Abstract:In this study the world’s first real time in-situ simultaneous small angle x-ray scattering (SAXS) and wide angle x-ray scattering (WAXS) characterization of supercritical nanoparticle formation was performed. In previous supercritical studies the reaction is treated as a ‘black box’ and the final product has been used to understand the process. In this study we open up the black box and directly reveal the mechanism behind sol-gel reactions in supercritical CO2. The brilliance of the APS source and the design of the supercritical reaction chambers played a critical role in successfully exploring the key parameters in the formation of high quality nanoparticles in supercritical fluids. By the current set-up the supercritical sol-gel nanoparticle formation can be controlled and altered by changing the process parameters. This means that the particle properties can be tailor-made by fine-tuning the process parameters.